Tribological study of trioctylthiotriazine derivative as lubricating oil additive

A novel ashless and non-phosphorus oil-soluble compound, 2,4,6-trioctylthio-1,3,5-triazine(OTT) was synthesized with the reaction of cyanuric chloride and sodium octyl mercaptan in tetrahydrofuran at reflux temperature for 8 h. The tribological properties of OTT and octylthiol(OT) as additives in a liquid paraffin were evaluated and compared using both a four-ball wear tester and a four-ball EP wear test machine. The results show that OTT behaves extremely better than OT as anti-wear and friction-reducing additive, while OT exhibits more excellent extreme pressure property. The element composition and chemical state of the films generated on steel counterface were investigated with a scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). It was found that tribological reaction occurred during the rubbing process and a protective film containing FeS, FeSO4 and some organic nitrogen compounds was formed on the worn surface.